Preparation and characterization of 6-O-caffeic acid chitosan

Abstract

The modified chitosan retains the excellent properties of chitosan and can broaden its application. In this paper, an approach of protection-deprotection was used to synthesize 6-O-caffeic acid chitosan with chitosan as the raw material. Firstly, the free amino group on the 2-position carbon of chitosan was protected by phthaloylation, and then the-OH of 6-position carbon of chitosan reacted with caffeic acid by ester condensation. Finally, in the presence of hydrazine hydrate, the amino group was deprotected to form 6-O-caffeic acid chitosan. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) characterized the structures of the intermediates and products. The results showed that 6-O-caffeic acid chitosan was successfully obtained. Thermogravimetric analysis indicated that 6-O-caffeic acid chitosan had better thermo-stability than chitosan in nitrogen. This will expand the application of chitosan in vaious fields.